Managing EGR for MPG

[DRW]

Originally Posted by MetroMPG

Would a cooler cause water vapor to condense out of the exhaust? If so, would you have to have a way to periodically drain it?

Good point. I suppose I'll have to make sure it's higher than the inlet/outlet so it doesn't collect water or other liquid deposits of any sort.

Originally Posted by MetroMPG

Noticed another point in the VX article linked in that supports the EGR mod idea, but for a reason not yet raised in this thread:

It looks like I'd have to modify the EGR valve to get more flow out of it, and that's something I'm not ready to do. There's too many variables, and no tools to monitor flow accurately. I like the idea of balancing lean burn with EGR. Maybe I can plug in a section of code that sets EGR duty cycle to max whenever lean burn mode is active. So many ideas to try out, and so few hours in a day.

Originally Posted by MetroMPG

Now that i've got datalogging capability I'll also have to look to see whether EGR control is one of the parameters I can monitor. (I know it's in the list of parameters in the software, but the car doesn't necessarily have all the sensors the software can monitor.)

Nice logger. IIRC OBDII cars have EGR temp sensors.

[Compaq888]

Originally Posted by Sludgy

I understand why WAI helps fuel economy. Basically, it allows the engine to suck in a smaller mass of air into the engine throught a wider throttle setting. This reduces manifold vacuum, and therefore reduces engine pumping losses.

Another way to achieve the same effect could be by adding exhaust to the intake. First, exhaust is hot, so it would have an WAI effect. Secondly, it would reduce the O2 content of the intake, so less fuel would be added during closed loop operation.

EGR is often used to reduce NOx emissions. Has any Gassaver tested EGR for fuel economy?

Not always true. I have data to back up that the WAI doesn't always improve fuel economy. I actually lost a bet to Matt doing this. Drove 200miles for nothing too. Well not for nothing. Good experiment.

All cars are different. Some cars with WAI will improve fuel economy while others won't. You have to know what your engine and ecu want. That is what all of us are after.

[DRW]

I suppose it would help to know where the intake air temp sensor is located. On my car it's just after the air filter, while the EGR passage is much farther downstream after the throttle body. So any temp rise from EGR would go unnoticed by the IAT sensor.

A wise person once said,'There's never been a problem made worse by knowing too much about it'.

[Toysrme]

EGR will not provide a mileage boost in this case. It reduces power output, which will cause you to do nothing more than use a wider throttle angle to increase power output to previous types of levels.




One thing that you people have not thought about is what the EGR system does. EGR is the absolute bane of any, and all modern preventative maintenance. EGR cakes the entire intake tract, pluemn chamber, throttle body/carb plates with carbon from one end to another. The EGr valves themselves eventually stick, any idle valves that are present are commonly stuck with carbon due to the very small orifaces.
Increasing EGR flow will decrease the amount of time between carbon cleanings which for many cars is noticeable within 9-12 months.

The carbon build-up is also responcible for relatively signifigant horsepower losses due to the decrease in charge velocity it from the carbon build-up in the intake tract. (Outright port sizing & flow capacity is only 50% of a charge equation. Velocity is the other 50%.)



So you're not only cutting power from margionally leaner mixtures, you're also decreasing power over time. *Most* EGR eqipped engines will loose a measureable 5-10bhp loss over a year from a completely clean intake tract, to a dirty one.




Carbon build-up is the cause of so many more modern (Read Japanese/European) makers moving to varriable valve timing, and electronic throttle. To remove EGR systems, and their nessesative minor maintenance issues all-together.

[omgwtfbyobbq]

Granted, they do coke up a bit, but imle they tend to last as long as oxygen sensors and other wearable emissions equipment. I had about 130k miles before I replaced mine, and the intake did not have very much coke around it. Nothing a little scrubbing couldn't take off. In terms of hp losses, I'd like to see more info on that if possible.

[rh77]

Enter... Seafoam! (or whatever)

RH77

[onegammyleg]

Originally Posted by Toysrme

*Most* EGR eqipped engines will loose a measureable 5-10bhp loss over a year from a completely clean intake tract, to a dirty one..

Hmm . so my 1994 Swift (metro) has lost somehwere between 60 and 120 hp.
Thats darned amazing since it only had 50 in the begining.- I must be running on overunity cosmic energies now.

All hail to me , Ive tapped the ether. !!

[DRW]

I've upped the egr duty cycle on my car and haven't seen any difference so far. It still drives like a normal car so I haven't reached the point of using too much egr. I have a feeling this is one of the areas where the factory settings are close to optimum.

[Toysrme]

Originally Posted by omgwtfbyobbq

Granted, they do coke up a bit, but imle they tend to last as long as oxygen sensors and other wearable emissions equipment. I had about 130k miles before I replaced mine, and the intake did not have very much coke around it. Nothing a little scrubbing couldn't take off. In terms of hp losses, I'd like to see more info on that if possible.

It's not the failure of said items. It's simply having to do the maintenance in dissisembling them & cleaning them at some point. And that itnerval increasing.
The carbon induced at a relatively high rate from EGR is the prime reason for newer engines with ability to change intake valve timing, and electronic throttle plate control to have replaced EGR systems that "worked" otherwise perfectly fine.

Originally Posted by onegammyleg

Hmm . so my 1994 Swift (metro) has lost somehwere between 60 and 120 hp.
Thats darned amazing since it only had 50 in the begining.- I must be running on overunity cosmic energies now.

All hail to me , Ive tapped the ether. !!

No... You just mis-read what I said & babbled on about it like an idiot.




rh77 - Seafoam is excellent at cleaning combustion chambers, and the very hot area around the intake valve bowl area. Not as good as water injection, but it's probably running a good second.
Seafoam, nor any other "top end", or Sprayed cleaner" will clean carbon off the intake porting, and pluemn chamber<s> simply by being sprayed on it. Doing so requires some muscle effort.



AFA talking about cooling EGR. There are random engines about that have intrigrated their throttlebody warming circuit to the EGR pipe. Which serves to heat the coolant faster, and lower the temp of EGR to some degree.





ZugyNA / maxc - To really get an economy benifit with water injection. You need to be running the engine passed the pre-ignition limit of the normal fuel. A combination of high effective compression, and being lean. If you can not achive that. Water does nothing more that keep the combustion chamber & intake bowl in the head "pretty" and carbon free.



A common misconception is that water injection prolongs the combustion event, and turns to super expanding steam. Both of which adds power output. Neither of which are true when it comes to increasing power output. It's myth. Water injection on it's own, when you are not running an engine near the brink of detonation, reduces power output.

[onegammyleg]

Originally Posted by onegammyleg
Hmm . so my 1994 Swift (metro) has lost somehwere between 60 and 120 hp.
Thats darned amazing since it only had 50 in the begining.- I must be running on overunity cosmic energies now.

All hail to me , Ive tapped the ether. !!

&#168;No... You just mis-read what I said & babbled on about it like an idiot.&#168;

UMM ., NO.- I caught you out on an unsubstantiated over statement.

I personally don't agree with your figures or time estimates , and the notion of the need to pull down and cleaning the intake tract every 9 to 12 months is just preposterous.

You implied in your posts that the carbon builds up and that a person will lose between 5 and 10hp within 1 year .
If this is so the carbon would keep building up until the intake flowed so little power would be almost nothing - UNLESS ,, your estimation was an over dramatization of whats happening or there is some magic fairy self cleaning action going on in the intake.

Either way .. it shows that the problem is not as severe as you implied , and definitely does not warrant the paranoic response of cleaning the intake every 12 months.

Even a 5 mm thick crust of carbon deposits on the walls of the intake tract would have only minor impact on power.
If the carbon blocks a vacuum port or shrouds the throttle butterfly (as previously discussed in here) or prevents the EGR valve from opening and closing properly that that can cause serious drive ability issues.

sheesh.

If you think I am wrong , please submit the information to back up your claim to be considered.
I expect that this would be from a reliable source - eg an auto maker service bulletin would do nicely.

If you cant back it up , please keep your opinions to yourself and refrain from calling people idiots.
I have only seen such disrespect from know nothing 1st year apprentices , from which group I assume you belong to.